In combination with silicon, oxide appears as silicon dioxide SiO2. It can be deposited in very thin, electric stable, and uniform layers.

Silicon dioxide, or just dioxide, is very resistant and can only be etched by hydrofluoric acid HF. Water or other acids don't affect oxide; because of metal ions, alkaline lye (KOH, NaOH) can't be used (both KOH and NaOH in contrast are important for anisotropic wet etch in micromechanics). The chemical reaction of dioxide and HF is as follows: